1. Field of the Invention
This invention relates to a method for producing or treating a fibrous web, in particular a paper web or paperboard web, with which at least one property of the fibrous web, in particular a CD (cross direction) profile, such as the moisture CD profile, is established such that a preselected quality range is adhered to or a predefined quality value is undershot by no more than a predefined deviation.
In addition this invention relates to an apparatus for producing or treating a fibrous web, in particular a paper web or paperboard web, having a way which is constructed such that a property of the fibrous web, in particular a CD profile such as the moisture CD profile, is established therewith such that a preselected quality range is adhered to or a predefined quality value is undershot by no more than a predefined deviation.
2. Description of the Related Art
On paper machines there are CD profile actuating apparatuses, in particular for the moisture content of the paper web, whose power consumption lies in the megawatt range. Considerable savings in power can be made therefore by improving the CD profile actuating apparatuses.
A known way to save power is to minimize the mean load of the actuating elements. A certain actuator profile setting, which is calculated using a control algorithm, is required to improve the moisture CD profile. In most CD profile control apparatuses the mean actuator setting is a preselected value. In some apparatuses the actuator setting is slowly and continuously changed with the aim of minimizing the mean value without impairing the CD profile control in its function. The minimum is usually reached when the CD actuator with the smallest actuating value reaches the zero limit or a preselected absolute minimum value. A further decrease of the mean value of all actuators would change the actuating profile shape and impair the paper quality.
What is needed in the art is to enable a further saving of power.